Design for additive manufacturing.

The estimator on this site prices geometry. Volume, height, how much of its bounding box the part fills and the infill you pick all move the number, so a design decision is a price decision before it is anything else. This page is the short version of what to read first, and the links go to the source rather than to a summary of it.

Every link below opens in a new tab and goes to a site we do not run. The three diagrams are ours.

Material selection

Start from what the part has to survive rather than from a strength figure on a datasheet. Published numbers are measured on test coupons, so a printed part with layer lines, infill and a chosen orientation will not match them.

• Prusa Research Filament Material Guide A comparison table of around nineteen filament types with print temperatures and properties.
• Polymaker Filament Guide Selection by property and by application, rather than by product name.

Published by Prusa Research and Polymaker.

For the six materials this shop runs and what each is poor at, see the materials page.

Overhangs and bridging

A wall that leans up to about 45 degrees from vertical still lands on the layer beneath it, so it prints without support. Past that, less and less of each layer has anything under it. Support material fixes it, and support costs print time, material and a witness mark where it was removed.

Short spans pull straight as they cool. Longer ones sag in the middle, and every layer above a sagged bridge inherits the shape, so the fix belongs in the model rather than in the slicer.

• Protolabs Network (Hubs) How to design parts for FDM 3D printing The 45 degree rule, bridging, elephant foot, holes and anisotropy in one place.
• UltiMaker Design for FDM 3D printing Overhang limits, bridge spans, wall and hole minimums, and assembly clearances.
• Prusa Knowledge Base Poor bridging Why a bridge sags and what to change when it does.
• Prusa Knowledge Base Support material When geometry genuinely needs support, and what that costs you.

Published by Protolabs Network, UltiMaker and Prusa Research.

Infill selection

Infill is the lattice inside the walls. More of it is stiffer and heavier, and it takes longer to print. The pattern decides which direction that stiffness runs and whether the cells are closed. Worth knowing before you reach for the density slider: the guides below make the case that adding walls buys strength more cheaply than adding infill does.

The estimator carries an infill slider, so you can see what a density change does to the price of your own part before you commit to it.

• Protolabs Network (Hubs) Optimal shell and infill parameters Shells against infill, and what density actually buys in strength.
• Protolabs Network (Hubs) Infill in 3D printing Density bands for different jobs and eight patterns compared.
• Prusa Knowledge Base Infill The slicer side reference: what each setting does and where it lives.

Published by Protolabs Network and Prusa Research.

General DFAM reading

Wider than one feature at a time. The first is a primer, the last is a research level survey.

• Prusa Knowledge Base Modeling with 3D printing in mind A primer on designing for FFF, written for people who already model.
• MIT OpenCourseWare 2.008 Lecture 23, Additive Manufacturing Undergraduate lecture notes on additive manufacturing, published CC BY NC SA.
• Andrew Ellis Ellis' Print Tuning Guide An open source handbook for tuning an FDM machine, feature by feature.
• NIST Design Rules for Additive Manufacturing A literature review and taxonomy of published design rules. Public domain.
• MakerWorld MakerWorld A large library of ready made 3D printable designs shared by their makers.

Published by Prusa Research, MIT OpenCourseWare, Andrew Ellis, NIST and MakerWorld.

About the diagrams

The three diagrams on this page were drawn for it here at Seabright Mechanical and are ours.